#include <GL/glut.h>

GLfloat mat_red_diffuse[] = { 0.7, 0.0, 0.1, 1.0 };
GLfloat mat_green_diffuse[] = { 0.0, 0.7, 0.1, 1.0 };
GLfloat mat_blue_diffuse[] = { 0.0, 0.1, 0.7, 1.0 };
GLfloat mat_yellow_diffuse[] = { 0.7, 0.8, 0.1, 1.0 };
GLfloat mat_specular[] = { 1.0, 1.0, 1.0, 1.0 };
GLfloat mat_shininess[] = { 100.0 };
GLfloat knots[8] = { 0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0 };
GLfloat pts1[4][4][3], pts2[4][4][3];
GLfloat pts3[4][4][3], pts4[4][4][3];
GLUnurbsObj *nurb;
int u, v;

static void
display(void)
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glCallList(1);
	glFlush();
}

int
main(int argc, char **argv)
{
	glutInit(&argc, argv);
	glutCreateWindow("molehill");
	glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
	glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);
	glEnable(GL_LIGHTING);
	glEnable(GL_LIGHT0);
	glEnable(GL_DEPTH_TEST);
	glEnable(GL_AUTO_NORMAL);
	glEnable(GL_NORMALIZE);
	nurb = gluNewNurbsRenderer();
	gluNurbsProperty(nurb, GLU_SAMPLING_TOLERANCE, 25.0);
	gluNurbsProperty(nurb, GLU_DISPLAY_MODE, GLU_FILL);

	/* Build control points for NURBS mole hills. */
	for(u=0; u<4; u++) {
		for(v=0; v<4; v++) {
			/* Red. */
			pts1[u][v][0] = 2.0*((GLfloat)u);
			pts1[u][v][1] = 2.0*((GLfloat)v);
			if((u==1 || u == 2) && (v == 1 || v == 2))
				/* Stretch up middle. */
				pts1[u][v][2] = 6.0;
			else
				pts1[u][v][2] = 0.0;

			/* Green. */
			pts2[u][v][0] = 2.0*((GLfloat)u - 3.0);
			pts2[u][v][1] = 2.0*((GLfloat)v - 3.0);
			if((u==1 || u == 2) && (v == 1 || v == 2))
				if(u == 1 && v == 1)
					/* Pull hard on single middle square. */
					pts2[u][v][2] = 15.0;
				else
					/* Push down on other middle squares. */
					pts2[u][v][2] = -2.0;
			else
				pts2[u][v][2] = 0.0;

			/* Blue. */
			pts3[u][v][0] = 2.0*((GLfloat)u - 3.0);
			pts3[u][v][1] = 2.0*((GLfloat)v);
			if((u==1 || u == 2) && (v == 1 || v == 2))
				if(u == 1 && v == 2)
					/* Pull up on single middple square. */
					pts3[u][v][2] = 11.0;
				else
					/* Pull up slightly on other middle squares. */
					pts3[u][v][2] = 2.0;
			else
				pts3[u][v][2] = 0.0;

			/* Yellow. */
			pts4[u][v][0] = 2.0*((GLfloat)u);
			pts4[u][v][1] = 2.0*((GLfloat)v - 3.0);
			if((u==1 || u == 2 || u == 3) && (v == 1 || v == 2))
				if(v == 1)
					/* Push down front middle and right squares. */
					pts4[u][v][2] = -2.0;
				else
					/* Pull up back middle and right squares. */
					pts4[u][v][2] = 5.0;
			else
				pts4[u][v][2] = 0.0;
		}
	}
	/* Stretch up red's far right corner. */
	pts1[3][3][2] = 6;
	/* Pull down green's near left corner a little. */
	pts2[0][0][2] = -2;
	/* Turn up meeting of four corners. */
	pts1[0][0][2] = 1;
	pts2[3][3][2] = 1;
	pts3[3][0][2] = 1;
	pts4[0][3][2] = 1;

	glMatrixMode(GL_PROJECTION);
	gluPerspective(55.0, 1.0, 2.0, 24.0);
	glMatrixMode(GL_MODELVIEW);
	glTranslatef(0.0, 0.0, -15.0);
	glRotatef(330.0, 1.0, 0.0, 0.0);

	glNewList(1, GL_COMPILE);
	/* Render red hill. */
	glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_red_diffuse);
	gluBeginSurface(nurb);
	gluNurbsSurface(nurb, 8, knots, 8, knots,
	                4 * 3, 3, &pts1[0][0][0],
	                4, 4, GL_MAP2_VERTEX_3);
	gluEndSurface(nurb);

	/* Render green hill. */
	glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_green_diffuse);
	gluBeginSurface(nurb);
	gluNurbsSurface(nurb, 8, knots, 8, knots,
	                4 * 3, 3, &pts2[0][0][0],
	                4, 4, GL_MAP2_VERTEX_3);
	gluEndSurface(nurb);

	/* Render blue hill. */
	glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_blue_diffuse);
	gluBeginSurface(nurb);
	gluNurbsSurface(nurb, 8, knots, 8, knots,
	                4 * 3, 3, &pts3[0][0][0],
	                4, 4, GL_MAP2_VERTEX_3);
	gluEndSurface(nurb);

	/* Render yellow hill. */
	glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_yellow_diffuse);
	gluBeginSurface(nurb);
	gluNurbsSurface(nurb, 8, knots, 8, knots,
	                4 * 3, 3, &pts4[0][0][0],
	                4, 4, GL_MAP2_VERTEX_3);
	gluEndSurface(nurb);
	glEndList();

	glutDisplayFunc(display);
	glutMainLoop();
	return 0;             /* ANSI C requires main to return int. */
}
